I've already commented/speculated on this. A bone spur is a very vague expression. Where is it? Which tendon is it pressing? Why haven't they opted for surgery? Since when KG has it?
My bet is that KG has been suffering from patellar tendonitis, which is pretty common in pro basketball players - especially those who had growth spurts in their youth. As a consequence, micro-tears of the tendon may occur (the injury), as well as some calcification - the "bone spur", that's basically soft tissue (the tendon) turned into bone.
Generally rest and antiinflammatories (even steroids in more aggressive therapies) can solve the issue (the tendonitis is chronic, but that's why you see so many NBA players using knee braces/straps and icing their knees right after the games....).
When rest doesn't work and the calcification is too severe, well, surgery is an option (and mandatory in case there's a rupture). But let's jut hope this doesn't happen. NOBODY WANTS TO PERFORM SURGERY ON THE PATTELAR TENDON. It will weaken the tendon (as tissue has to be removed) and increase the risks of a rupture. You basically have a McDyess situation or an exponentially high risk of having a McDyess situation. And McDyess was like the absolute best case scenario one could think of, a true miracle - and in spite of that, he's not even close of being the same player, from a physical point of view, he was before the surgery. This is the worst case scenario - rest doesn't work and surgery (that is simple in itself) must be performed.
Or maybe the "bone spur" is merely the scar tissue that resulted of the healing of a strain in the medial head of the gastrocnemius - that would be nice, but it doesn't seem to be the case.
Anyway, cortisone shots, ultrasounds and deep frictions should be enough to put him ready for a month of playoff basketball.